A Systematic Approach to Multiple Breath Nitrogen Washout Test Quality

Area of Science:

• Pulmonary Function Testing
• Respiratory Physiology

Background:

• Accurate multiple breath washout (MBW) outcomes depend on device operation, subject breathing patterns, and data interpretation.
• Existing recommendations for acceptable MBW tests guided the development of a systematic evaluation protocol.

Purpose of the Study:

• To develop and evaluate a protocol for systematically assessing MBW measurements based on technical and breathing pattern criteria.
• To improve the reliability and consistency of MBW data interpretation.

Main Methods:

• 50 MBW test occasions were reviewed by an experienced operator for technical quality and breathing pattern representativeness.
• Inter-observer agreement was assessed using qualitative and quantitative criteria across eight MBW operators.
• Kappa statistics were used to evaluate agreement (n=20 test occasions).

Main Results:

• Qualitative criteria led to the rejection of 46/168 trials (16.6% technical, 10.7% breathing pattern).
• Reviewer agreement was good with qualitative criteria and significantly improved with quantitative criteria (κ=0.53–0.83% to κ=0.73–0.97%).
• Increased exclusion of test occasions occurred with quantitative criteria in this retrospective analysis.

Conclusions:

• Systematic review application enhanced inter-observer agreement for MBW test evaluations.
• The improved agreement in evaluating MBW tests did not impact the final reported outcomes.